file-systems: Add FAT32 support.

* gnu/build/file-systems.scm (%fat32-endianness, fat32-superblock?,
read-fat32-superblock, fat32-superblock-uuid, fat32-uuid->string,
fat32-superblock-volume-name, check-fat32-file-system): New variables.
(%partition-label-readers, %partition-uuid-readers, check-file-system): Add
fat support.
(latin1->string): New variable.
(null-terminated-latin1->string): Use latin1->string.

Merge branch 'master' into python-tests

services: Add 'special-files-service-type'.

* gnu/build/activation.scm (activate-/bin/sh): Remove.
(activate-special-files): New procedure.
* gnu/services.scm (activation-script): Remove call to
'activate-/bin/sh'.
(special-files-service-type): New variable.
(extra-special-file): New procedure.
* gnu/services/base.scm (%base-services): Add SPECIAL-FILES-SERVICE-TYPE
instance.
* gnu/tests/base.scm (run-basic-test)[special-files]: New variables.
["special files"]: New test.

Add (gnu build shepherd).

* gnu/build/shepherd.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.

linux-container: Add 'container-excursion*'.

* gnu/build/linux-container.scm (container-excursion*): New procedure.
* tests/containers.scm ("container-excursion*")
("container-excursion*, same namespaces"): New tests.

linux-container: Add comment on exception handling.

* gnu/build/linux-container.scm (run-container): Add note about writing
the exceptions.

linux-container: Do not rely on 'isatty?'.

This avoids problems where 'isatty?' return #t but 'ttyname' fails with
ENOTTY or such.

* gnu/build/linux-container.scm (mount-file-systems): Remove call of
'isatty?'.  Directly call 'ttyname' and catch 'system-error'.

activation: Set the right owner for home directories.

This fixes a regression introduced in
ae763b5b0b7d5e7316a3d0efe991fe8ab2261031 whereby home directories and
skeletons would be root-owned.

* gnu/build/activation.scm (copy-account-skeletons): Make 'directory' a
keyword parameter.  Add #:uid and #:gid and honor them.
[set-owner]: New procedure.
(activate-user-home): Add call to 'getpw' and 'chown'.  Pass UID and GID
to 'copy-account-skeletons'.
* gnu/tests/base.scm (run-basic-test)["skeletons in home directories"]:
Test file ownership under HOME.

system: Create home directories once 'file-systems' is up.

Fixes <http://bugs.gnu.org/21108>.
Reported by Andy Patterson <ajpatter@uwaterloo.ca>
and Leo Famulari <leo@famulari.name>.

* gnu/build/activation.scm (activate-users+groups)[activate-user]: Pass
  #:create-home? #t iff CREATE-HOME? and SYSTEM?.
(activate-user-home): New procedure.
* gnu/system/shadow.scm (account-shepherd-service): New procedure.
(account-service-type)[extensions]: Add SHEPHERD-ROOT-SERVICE-TYPE
extension.
* gnu/tests/base.scm (run-basic-test)["home"]
["skeletons in home directories"]: New tests.
* gnu/tests/install.scm (%separate-home-os, %separate-home-os-source)
(%test-separate-home-os): New variables.

file-systems: Do not read superblocks past the end of a device.

Fixes <http://bugs.gnu.org/25573>.
Reported by Alex Kost <alezost@gmail.com>.

* gnu/build/file-systems.scm (seek*): New procedure.
(read-superblock): Use it instead of 'seek' and ensure it returns
OFFSET.

Merge branch 'master' into python-tests

system: Add btrfs file system support.

* gnu/build/file-systems.scm (%btrfs-endianness, btrfs-superblock?,
  read-btrfs-superblock, btrfs-superblock-uuid,
  btrfs-superblock-volume-name, check-btrfs-file-system): New variables.
  (%paritition-label-readers, %partition-uuid-readers): Add btrfs
  readers.
* gnu/system/linux-initrd.scm (linux-modules): Add btrfs modules when a
  btrfs file-system is used.
* gnu/tests/install.scm (%btrfs-root-os %btrfs-root-os-source,
  %btrfs-root-installation-script, %test-btrfs-root-os): New system
  test.
* doc/guix.texi: Adjust accordingly.

Fixes <http://bugs.gnu.org/19280>.

file-systems: Refactor file-system predicates.

* gnu/build/file-systems.scm (partition-field-reader,
  read-partition-field, %partition-label-readers,
  %partition-uuid-readers, read-partition-label, read-partition-uuid):
  New variables.
  (partition-predicate, partition-label-predicate,
  partition-uuid-predicate, luks-partition-uuid-predicate): Use
  partition field readers.
  (find-partition): New variable.
  (find-partition-by-label, find-partition-by-uuid,
  find-partition-by-luks-uuid): Use find-partition-by.

file-systems: Refactor check-file-system.

* gnu/build/file-systems.scm (check-file-system): Use file-system type
  specific checker.
  (check-ext2-file-system): New variable.

file-systems: Refactor file system detection logic.

* gnu/build/file-systems.scm (read-superblock,
  null-terminated-latin1->string): New variables.
  (sub-bytevector): Move to general section.
  (ext2-superblock?, read-ext2-superblock): New variables.
  (ext2-superblock-uuid, ext2-superblock-volume-name): Use
  sub-bytevector and null-terminated-latin1->string.
  (%ext2-sblock-magic, %ext2-sblock-creator-os, %ext2-sblock-uuid,
  %ext2-sblock-volume-name): Inline constants.
  (luks-superblock?, read-luks-header): New variables.
  (%luks-header-size, %luks-magic): Inline.
  (partition-label-predicate, partition-uuid-predicate,
  luks-partition-uuid-predicate): Use new functions.

Merge remote-tracking branch 'origin/master' into staging

gnu: cross-base: Move phases to (gnu build cross-toolchain).

* gnu/packages/cross-base.scm (cross-gcc-arguments) <#:phases>: Use
'cross-gcc-build-phases', and move body cross-toolchain.scm.
(cross-gcc): Add #:imported-modules.  Add (gnu build cross-toolchain) to
 #:modules.
* gnu/build/cross-toolchain.scm: New file, with code from
'cross-gcc-arguments'.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.

Merge branch 'master' into staging

Merge branch 'master' into python-build-system

gnu: Allow nfs file systems to be automatically mounted.

* gnu/build/file-systems.scm (mount-file-system): Append target addr= when
mounting nfs filesystems.